This invention pertains to optical alignment systems. It pertains particularly to line of sight aligning devices for use with optical instruments having viewing openings requiring precise alignment with the line of sight of the viewer.
In the field of optics there are many optical instruments which, for their proper and accurate use, require precise alignment of the line of sight of the viewer with a viewing opening in the instrument. This is the case, for example, in Hill, U.S. Pat. No. 4,109,237 and Hill, U.S. Pat. No. 4,393,366 both of which pertain to apparatus and method for identifying individuals through their retinal vasculature patterns. The apparatus employed directs a beam of light into the eye of the subject and reads the retinal vasculature pattern from the reflected light. The resulting information then is used for identification of the subject.
In this sequence, it is imperative that the line of sight of the subject be located precisely with respect to the analyzing instrument in order to obtain reproduceable results.
Without mechanical assistance, precise location inherently is difficult of achievement. It is difficult for a viewer, unassisted, to align his eye precisely with the viewing opening of an instrument.
It accordingly is the general purpose of the present invention to provide an aligning device for use with optical instruments having viewing openings requiring precise alignment of the line of sight of the viewer.
It is a further object of the present invention to provide an optical aligning device which is simple, easy to use, usable in conjunction with a wide variety of optical instruments, and highly accurate.
Further objects of the present invention are the provision of an optical aligning device the application of which is obvious intuitively even to the technologically naive, being readily understood and easily mastered with minimum training time.
Other important objects of the present invention are the provision of an optical alignment device the use of which is independent of the viewer's refractive error, which does not require focusing, which controls or compensates for four of the six degrees of freedom of positioning of the viewer's head/eye (translation of the head up and down, and side to side; and angular rotation of the eye up and down, and side to side); which is monochromatic so that there is no color blindness problem; and which does not require use of special lenses or eyeglasses.
The foregoing and other objects of this invention are achieved by an optical aligning device which, broadly considered, comprises, in combination with the device, fixation target generating means operative to generate a line of multiple fixation targets spaced along the optical axis of the device, whereby to enable the viewer, by aligning his line of sight with the line of multiple fixation targets, to position his eye precisely on the optical axis of the device.
The fixation target generating means broadly comprises multiple light reflection (ghost image) generating means which in turn comprises a light emitting diode or other light source directed against a double coated mirror which is so constructed as to develop the multiple ghost images spaced along the optical axis of the device. By positioning his eye so that the ghost images are directly in line, the viewer accordingly is assured that his eye, or line of sight, is located precisely on the optical axis of the optical instrument.